Continuous Bandwidth Detection for FLVPlayback

I have a player for live streaming (from FMS), based on FLVplayback, written in AS3. It already works with bandwidth detection at the beginning by reading an smil file. I need bandwidth detection code that does the following: -Starts by playing the lowest-quality video available -During playback, continuously tests the bandwidth and, if necessary, switches versions of the file I would prefer a single class in an .as file that I can plug into my existing program (plus a demo of it working with an flvplayback component).